Modeling Low Temperature C-V Profiling in Blocked Impurity Band Detectors

Silicon Blocked Impurity Band (BIB) detectors are state-of-the-art devices to detect light in the near to mid infrared range (5-40 ? m). Numerical modeling of BIB detectors is performed using a four-region finite difference approach to study the role of space charge in C-V (capacitance-voltage) profiling of minority carrier doping and the role of blocking layer thickness and minority doping concentration in alternate bias operation. Compensation in the blocking layer is found to play a critical role in determining the net voltage drop in this part of the device under alternate polarity bias. The effect of space charge at the blocking layer/active layer interface on the measured low temperature C-V distribution is modeled as a function of the doping interface between the two layers. The magnitude of the space charge can cause large deviations in the measurement of minority doping concentration from the idealized case which assumes a space-charge free blocking layer and interface. Accurately determining these minority doping concentrations is a crucial step toward solving material growth challenges in proposed far infrared Ge and GaAs devices.